Apparatus for removing dust accretions from a smelting furnace

ABSTRACT

The invention relates to an apparatus for mechanically breaking up and detaching dust accretions created by process gases and accumulated on the inner walls of a suspension smelting furnace and/or a waste heat boiler permanently connected to the suspension smelting furnace. According to the invention, on the outer surface ( 7,13 ) of the wall of a suspension smelting furnace ( 1 ) and/or a waste heat boiler ( 6 ), in the vicinity of the connecting point ( 5 ) of the suspension smelting furnace and the waste heat boiler, there is installed at least one striker device ( 8,14 ), whereby there can be created a mechanical impact effect and mechanical contact between the apparatus ( 8,14 ) and at least one of the dust accretions ( 12,19 ).

The present invention relates to an apparatus for removing dustaccretions from a suspension smelting furnace used in the smelting ofsulfidic raw materials, such as ores or concentrates, containing usefulmetals, such as copper, nickel or lead.

In order to recover metals, such as copper, nickel or lead, fromsulfidic raw materials containing said materials, for instance from oresor concentrates, there is generally applied the suspension smeltingmethod, where the heat amounts contained by finely divided sulfidic rawmaterials are made use of. In addition to sulfidic raw materials, intothe reaction space of the suspension smelting furnace there is fedoxygen-containing gas, such as air, oxygen-enriched air or oxygen. Inaddition, to the reaction space there is fed for instance flue dustrecovered and recirculated from the exhaust gases of the suspensionsmelting furnace, as well as metallurgic slag-forming agent, flux. Inthe reaction space of the suspension smelting furnace, the solid andgaseous feed materials react with each other, so that in the bottom partof the suspension smelting furnace, there are formed at least two moltenphases, a slag phase and a matte phase contained by the metal to beutilized. The molten phases that are formed in the bottom part of thesuspension smelting furnace, i.e. in the settler, are removed from thesuspension smelting furnace at regular intervals. The sulfur dioxidebearing process gases created in the reaction space of the suspensionsmelting furnace are conducted, via the settler, to the uptake shaft ofthe suspension smelting furnace, and from the uptake shaft further to awaste heat boiler connected to the suspension smelting furnace, wherethe exhaust gases from the suspension smelting furnace are cooled, andat the same time the solids, i.e. flue dust, contained by the gas areremoved.

When the suspension smelting furnace exhaust gases are transferred fromthe uptake shaft of the suspension smelting furnace to the waste heatboiler, the flowing direction of the gases is changed from anessentially vertical direction to an essentially horizontal direction.Moreover, when the flowing area of the connecting aperture between theuptake shaft and the waste heat boiler is made essentially smaller thanthat of the uptake shaft in order to reduce the heat losses from thesuspension smelting furnace, contacts of sulfur dioxide bearing exhaustgases with the walls of the suspension smelting furnace cannot beavoided. Further, because the temperature of the exhaust gases isdropped towards the top part of the uptake shaft of the suspensionsmelting furnace, the molten particles contained in the exhaust gasesstart to be solidified, and when touching the uptake shaft walls, theyare attached to the wall, particularly in the vicinity of the connectingaperture between the uptake shaft and the waste heat boiler. Thus, inthe vicinity of the connecting aperture, there are accumulated dustaccretions that obstruct the flowing of the exhaust gases and musttherefore be broken apart.

It is an object of the invention to achieve an improved apparatus forbreaking up dust accretions created in the vicinity of the connectingpoint between the uptake shaft and successive waste heat boiler, in theinner parts of the uptake shaft and/or the waste heat boiler, so thatthe dust accretions do not essentially obstruct the flowing of theexhaust gases from the uptake shaft to the waste heat boiler.

According to the invention, in the vicinity of the connecting pointbetween the uptake shaft of a suspension smelting furnace and the wasteheat boiler connected to the uptake shaft, there is installed at leastone apparatus, whereby the dust accretions created in the vicinity ofthe connecting aperture of the uptake shaft and the waste heat boilercan be subjected to an impact effect in order to break up the dustaccretions and to drop them back to the bottom part of the uptake shaftof the suspension smelting furnace and/or to the bottom part of thewaste heat boiler. The apparatus according to the invention is attachedto the wall of the suspension smelting furnace and/or of the waste heatboiler, so that the impact effect achieved by means of the apparatus canbe conducted, through the wall of the suspension smelting furnace uptakeshaft and/or of the waste heat boiler to at least one dust accretionlocated inside the uptake shaft and/or waste heat boiler.

In order to break up dust accretions from the inside of the suspensionsmelting furnace uptake shaft and/or the waste heat boiler, in thevicinity of the connecting point between the suspension smelting furnaceuptake shaft and the waste heat boiler, by means of an apparatusaccording to the invention, in the wall of the uptake shaft and/or thewaste heat boiler, on the outer wall surface, in a locationcorresponding to the spot where the dust accretions are accumulated,there is installed at least one striker device. By means of the strikerdevice, strokes are directed through the wall to the counterpart of thestriker device that serves as an anvil. In that end of the counterpartof the striker device, installed through the wall, that is placed insidethe uptake shaft and/or the waste heat boiler, which end at the sametime is the opposite end with respect to the striker device, there isfurther installed a striker element whereby a mechanical contact can beachieved between the striker element and the dust accretions to bebroken up. The force of the stroke hit by the striker element makes thedust accretions to be broken up and detached from the wall of the uptakeshaft and/or the waste heat boiler, so that they are dropped down, tothe bottom part of the uptake shaft on the uptake shaft side, and to thebottom part of the waste heat boiler on the waste heat boiler side.

Advantageously the striker device meant for breaking up dust accretionsoperates pneumatically, hydraulically or in some other advantageousmanner. The striker device may advantageously be arranged to operate sothat it hits the striker counterpart, serving as the anvil, atessentially regular intervals. Naturally the striker device can also bearranged to operate so that strokes are placed only in cycles, atessentially regular intervals, or so that single strokes are hitaccording to the need for breaking up the dust accretions, with respectto their degree of accumulation. In addition, the impact force of thestriker device provided in the apparatus according to the invention canadvantageously be adjusted, in which case the hardness and adhesioncaused by the composition of the dust accretions can be taken intoaccount.

The invention is explained more detail with reference to the appendeddrawing, where

FIG. 1 is a schematical side-view illustration of a preferred embodimentof the invention, seen in a partial cross-section, and

FIG. 2 is a schematical side-view illustration of another preferredembodiment of the invention, seen in a partial cross-section.

According to FIG. 1, the sulfur dioxide bearing gases that are createdduring the smelting that takes place in the reaction space 2 of asuspension smelting furnace 1 are exhausted through the settler 3 to theuptake shaft 4 of the suspension smelting furnace. The uptake shaft 4is, via the aperture 5, connected to the waste heat boiler 6 in order tocool down the sulfur dioxide bearing exhaust gases and in order torecover the solids that are exhausted along with the gases. In thevicinity of the aperture 5 between the uptake shaft 4 and the waste heatboiler 6, on the outer surface 7 of the wall of the uptake shaft 4,there is installed striker device 8. In order to enable the desiredoperation of the striker device 8, in an aperture arranged in the wall 9of the uptake shaft 4, there is installed a counterpart 10 of thestriker device 8, which counterpart serves as the anvil. At that end ofthe counterpart 10 that is left inside the uptake shaft 4, there isfurther installed an impact plate 11.

When the striker device 8 is used for breaking up the dust accretions 12accumulated inside the uptake shaft 4, the striker device 8 hits thecounterpart 10, which moves in parallel to the aperture arranged in thewall of the uptake shaft 4. The counterpart 10 further moves the impactplate 11, which directs an impact to the dust accretions 12. Owing tothe force of the impact, the dust accretions 12 are broken up anddropped downwardly in the uptake shaft 4.

According to FIG. 2, on the outer surface 13 of a waste heat boiler 6connected to the uptake shaft 4 of a suspension smelting furnace 1 viaan aperture 5, there is installed striker device 14. In order to enablethe desired operation of the striker device 14, in an aperture arrangedin the wall 15 of the waste heat boiler 6, there is installed acounterpart 17 for the striker device 14, said counterpart serving asthe anvil. Moreover, at the end of the counterpart 17 that is leftinside the waste heat boiler 6, there also is installed an impactelement 18.

The striker device 14 operates in a similar way as the striker device 8,so that a stroke hit by the striker device 14 to the counterpart 17moves the counterpart 17 so that the impact element 18 gets into contactwith the dust accretions 19 and breaks up the dust accretions 19attached on the wall of the waste heat boiler 6.

What is claimed is:
 1. An apparatus for mechanically breaking up anddetaching dust accretions created by process gases and accumulated onthe inner walls of a suspension smelting furnace and/or a waste heatboiler permanently connected to the suspension smelting furnace, theapparatus comprising: at least one linearly-acting striker deviceutilizing a single linear actuator, the striker device being mounted onthe outer surface of the wall of the suspension smelting furnace and/orwaste heat boiler, in the vicinity of the connecting point of thesuspension smelting furnace and the waste heat boiler, the at least onestriker device, creating a mechanical impact effect and mechanicalcontact between the apparatus and at least one of the dust accretions;and a counterpart for the at least one linearly-acting striker devicemovably installed in an aperture provided in the wall of the suspensionsmelting furnace and/or the waste heat boiler to receive strokes causedby the striker device and in order to direct the strokes to the dustaccretions accumulated in the suspension smelting furnace and/or wasteheat boiler, the counter part for the striker device being installedthrough the wall of the suspension smelting furnace and/or the wasteheat boiler in an aperture provided in the wall, an impact plateattached to the counterpart, the impact plate being installed on aninner side of the wall, aligned with the direction of the wall.
 2. Anapparatus according to claim 1, wherein the counterpart of the strikerdevice is, at the end that is opposite to the striker device, providedwith an impact element.
 3. An apparatus according to claim 1, whereinthe striker device is arranged to operate pneumatically.
 4. An apparatusaccording to claim 1, wherein the striker device is arranged to operatehydraulically.
 5. An apparatus according to claim 1, wherein the strikerdevice is arranged to operate electrically.